In electrostatographic printing, commonly known as xerographic printing or copying, an important process step is known as “fusing.” In the fusing step of the xerographic process, dry marking material, such as toner, which has been placed in imagewise fashion on an imaging substrate, such as a sheet of paper, is subjected to heat and/or pressure in order to melt or otherwise fuse the toner permanently on the substrate. In this way, durable images are rendered on the substrates.
Currently, the most common design of a fusing apparatus as used in commercial printers includes two rolls, typically called a fuser roll and a pressure roll, forming a nip therebetween for the passage of the substrate therethrough. Typically, the fuser roll further includes, disposed on the interior thereof, one or more heating elements, which radiate heat in response to a current being passed therethrough. The heat from the heating elements passes through the surface of the fuser roll, which in turn contacts the side of the substrate having the image to be fused, so that a combination of heat and pressure successfully fuses the image.
A design consideration which has recently become important in the office equipment industry is the avoidance of “flicker” with regard to a power system associated with the printing apparatus. “Anti-flicker” mandates, which basically require that the power consumption of the machine as a whole does not affect the behavior of other equipment, such as fluorescent lighting, within the same building, are of concern in many countries. Further, different countries have different power levels and AC frequencies associated with their wall outlets, and it is desirable to design a printing apparatus, particularly with regard to the fuser, that is suitable for different power supplies with minimum necessary modifications.